Centrifugal gas compressors



Dec. 6, 1966 G. R. WOOD 3,289,919

I CENTRIFUGAL GAS COMPRESSORS Filed NOV. 16, 1964 2 Sheets-Sheet 1FIG.|.

|NVENTOR= GARY R.WOOD, BY WJVM ATTORNEY 6 G. R. WOOD 3,289,919

CENTRIFUGAL GAS COMPRESSORS Filed NOV. 16, 1964 2 Sheets-Sheet 2 FFIG.2.

iNVENTOR= GARY R.WOOD, BYWQVW ATTORNEY United States Patent Ofiice3,289,919 Patented Dec. 6, 1966 3,289,919 CENTRIFUGAL GAS COMPRESSQRSGary R. Wood, Staunton, Va, assignor to Westinghouse ElectricCorporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov.16, 1964, Ser. No. 411,496 Claims. (Cl. 230114) inlets of constantspeed, centrifugal compressors for adjusting their outputs. Theadvantage and methods of operation of such vanes are fully disclosed inthe US. patents of H. F. Hagen, Nos. 1,846,863 and 1,999,413. Thecopending application of R. W. Wolfe and R. R. Young, Serial No.280,606, filed May 15, 1963, now Patout No. 3,251,539, discloses how themechanism for adjusting the spin inducing vanes of a centrifugalrefrigerant compressor can be used to move an outer wall of a radialdiffuser toward an opposite fixed wall of the diffuser for automaticallydecreasing the width of the diffuser when the vanes are adjusted towardsclosed positions. The inner end of an annular piston which adjust thespin vanes directly contacts a ring which is in contact with the movablewall of a diffuser when the vanes are near closed positions, and thewidth of the diffuser is decreased in direct proportion to the movementof the piston as it adjusts the vanes further towards fully closedpositions.

My invention is an improvement on that of the Wolfe- Young applicationin that it provides a leverage system between the inner end of such apiston and the movable wall of such a diffuser for reducing the rate ofmovement of the movable wall of the diffuser towards its fixed wallbelow that of the piston which causes such movement. In one embodimentof my invention, the inner end of an annular piston contacts ends oflevers after the piston has been moved a predeermined distance inwardly.The levers are pivoted to the movable diffuser wall with their otherends in contact with a fixed surface. When the piston is moved furtherinwardly, the levers are caused to move the movable wall inwardly. Thelevers have such ratios that the rate of inward movement of the movablewall is less than that of the piston after the piston has started theinward movement of the movable wall. Thus, the width of the diffuser isadjusted in accordance with flow rates in the intermediate and lowerranges of the flow rates, increasing efficiency, and reducing thetendency for occurrence of stall pulsations.

An object of my invention is to improve means used in centrifugalcompressors for automatically reducing the widths of radial diffuserwhen spin vanes are adjusted towards closed positions.

My invention will now be described with reference to the annexeddrawings, of which:

FIG. 1 is a side section of a compressor embodying my invention, withits spin vanes shown in fully open positions, and the radial diffuser inits widest position;

FIG. 2 is a view similar to the upper half of FIG. 1 except that thespin vanes are shown in almost fully closed positions, and the diffuserin its narrowest position, and

FIG. 3 is an end view of the movable diffuser wall with its pivotedlevers, with the levers in the positions shown by FIG. 1.

The compressor has a wall 10 around a converging inlet passage 11. Spinvanes 12, only two of which are shown by FIG. 1, are supported forrotation within the inner end portion of the passage 11 by pivot rods 13which are journalled for rotation within openings in the wall 14). Therods '13 are attached to inner ends of arms 14, the outer ends of whichhave hub portions 15 in which are journalled pins 16 having rollers 17in annular slot 18 in the inner surface of annular piston 19. The piston19 has an outwardly projecting portion 20' having an outer surface inslidable contact with cylindrical inner surface 21 of compressor wall 22which extends around the inner portion of the wall 10. The pistonportion 20 has a seal ring 23 in contact with the surface 21. The piston19 has a cylindrical surface to the right of its portion 20 in slidablecontact with cylindrical inner surface 24 of the wall 22, with thesurface 24 containing seal rings 25. The piston 19 has a cylindricalsurface 26 to the left of its portion 20 in slidable contact withcylindrical inner surface 28 of compressor wall29, the surface 28containing seal rings 35. The wall 29 has an outer cylindrical surface33 in contact with the surface 21. The surface 33 contains seal rings36.

The wall 22 has a passage 38 for the supply of fluid under pressureagainst the left side of the piston portion 20, and has a passage 39 forthe supply of fluid under pressure against the right side of the pistonportion 20.

A ring 42 is movable outer wall of radial diffuser 45, and has an innersurface 43 forming the outer surface of the difiuser, the inner surfaceof which is formed by outer surface 44 of compressor wall 46. Thering 42has a cylindrical outer portion in slidable contact with cylindricalinner surface 47 of the wall 29. The ring 42 has four, equally spacedapart, outwardly projecting portions 48 to which are pivoted by pin 49,levers 50. The levers 50 have at the outer sides of the pins 49, shortlengths, with their outer ends in contact with the inner, substantiallyradially extending surface of ring 52 which is press fitted to the wall29. The levers 50' have long lengths at the inner sides of the pins 49,the inner ends of which are adapted to be contacted by and moved axiallyinwardly by inner end 55 of the piston 19 when the latter is movedinwardly as will be described later.

A conventional rotor '75 attached by bolt 56 to shaft 57', has the usualblades 58 which discharge into the inner end of the radial diffuser 45.The usual outlet passage 60 formed between the wall 29 and anothercompressor Wall 61 extends around the outer end of the diffuser 45.Screws 7f} threaded into the wall 46 limit the innermost travel of theouter surface 43 of the diffuser 45 towards the inner surface 44 of thelatter.

Operation In operation, rotation of the blades 5% draws refrigerant gasthrough the passage 11 past the spin vanes 12. At a maximum load, thespin vanes 12 are in their wide open positions, and the diffuser 45 hasits largest width s0 that the compressor operates at full capacity. Theblades 58 compress the gas and supply it through the diffuser 45 and thepassage 60 as usual to a condenser which is not shown.

On a reduction in load, fluid under pressure from a conventional sourcewhich is not shown, is supplied through the passage 38 against the rightside of the piston portion 21), moving the piston 19 to the left, andcausing the vanes 12 to be rotated towards closed positions for inducingspin in the gas entering the inlet of the rotor 75, thereby reducing theoutput of the compressor as disclosed in the previously mentioned Hagenpatents. When the piston 19 is moved to the left sufiiciently to haveadjusted the vanes 12, for example, to about their mid-positions, theleft end 5'5 of the piston 19 moves against the inner ends of the levers50, causing through the pivoting of the latter to the ring 42, and thecontact of the outer ends of the levers 50 with the ring 52, the ring 42to be moved inwardly to narrow the diffuser 45. By way of example, thetravel of the piston may be 1.0", it may move 0.2" before its inner end55 contacts the inner ends of the levers 50, and the levers may have a4:1 ratio. Thus, the rate of inward movement of the ring 42, and theconsequent narrowing of the diffuser 45, is substantially less than therate of inward movement of the piston 19 which causes such narrowing.

FIG. 2 of the drawings, shows the piston 19 in its innermost position,shows a spin vane 12 near its closed position, and shows the diffuser 45almost closed.

Upon an increase in load, the reverse action takes place, fluid underpressure being supplied through the passage 39 against the left side ofthe piston portion 20, causing the piston 19 to move to the right and torotate the vanes 12 towards their open positions, and causing thediffuser 45 to be widened.

What is claimed is:

1. A centrifugal gas compressor having an axial inlet passage, havingspin vanes supported for rotation in said passage, having a bladedrotor, having an axial diffuser around said r-otor, said diffuser havinga wall movable to vary the width of said diffuser, means for rotatingsaid vanes towards closed positions, and leverage means movable by saidrotating means for moving said wall to narrow said diffuser when saidvanes are rotated towards closed positions at a rate less than the rateat which said vanes are rotated.

2. A centrifugal gas compressor having an axial inlet passage, havingspin vanes supported for rotation in said passage, having a bladedrotor, having an axial diffuser around said rotor, said diffuser havingan outer wall movable inwardly to decrease the width of said diffuser,means movable axially inwardly for rotating said vanes towards closedpositions, and leverage means moved inwardly by said axially movablemeans for moving said wall inwardly to narrow said diffuser when saidvane are rotated towards closed positions at a rate less than the rateat which said axially movable means is moved inwardly.

3. A centrifugal gas compressor comprising a rotor having radial flowblades, said compressor having a converging wall forming an axial inletpassage to said rotor,

said compressor having movable outer and fixed inner walls forming aradial diffuser around the tips of said blades, spin vanes in saidpassage having pivot rods journalled for rotation in said convergingwall, said compressor having another wall around said converging wall,said other wall having a cylindrical surface around and concentric withsaid inlet passage, an annular piston hav ing an intermediate portion inslidable contact with said surface, said piston having surfaces onopposite sides of said portion forming with said surface of said otherwall an annular cylinder passage, means for supplying fluid into theouter end of said cylinder passage against the outer side of said pistonportion for moving said piston inwardly, means for supplying fluid intothe inner end of said cylinder passage against the inner side of saidpiston portion for moving said piston outwardly, said piston havinganother surface radially inwardly of said piston surfaces with anannular slot therein, said pivot rods having arms extending radiallytherefrom, rollers in said slot journalled for rotation in the outerends of said arms, said slot, said rollers, said arms and said pivotrods being so arranged that when said piston is moved inwardly saidvanes are rotated towards closed positions, and leverage means betweenthe inner end of said piston and said movable wall for moving saidmovable wall towards said fixed wall when said pistonis moved inwardlyat a rate less than the rate at which said piston moves inwardly.

4. A centrifugal gas compressor as claimed in claim 3 in which saidinner end of said piston is spaced from said leverage means when saidvanes are in wide open positions and contacts said leverage means whensaid piston has been moved inwardly sufiiciently to have rotated saidvanes partially towards closed positions.

5. A centrifugal gas compressor as claimed in claim 4 in which saidleverage means comprises a plurality of levers pivoted to said movablewall, said levers having inner ends opposite said inner end of saidpiston, and havingouter ends in contact with a fixed surface of saidcompressor, and in which the pivots of said lever are closer to theirsaid outer ends than to their said inner ends.

References Cited by the Examiner UNITED STATES PATENTS LAURENCE v.EFNER, Primary Examiner.

1. A CENTRIFUGAL GAS COMPRESSOR HAVING AN AXIAL INLET PASSAGE, HAVINGSPIN VANES SUPPORTED FOR ROTATION IN SAID PASSAGE, HAVING A BLADEDROTOR, HAVING AN AXIAL DIFFUSER AROUND SAID ROTOR, SAID DIFFUSER HAVINGA WALL MOVABLE TO VARY THE WIDTH OF SAID DIFFUSER, MEANS FOR ROTATINGSAID VANES TOWARDS CLOSED POSITIONS, AND LEVERAGE MEANS MOVABLE BY SAIDROTATING MEANS FOR MOVING SAID WALL TO NARROW SAID DIFFUSER WHEN SAIDVANES ARE ROTATED TOWARDS CLOSED POSITIONS AT A RATE THAN THE RATE ATWHICH SAID VANES ARE ROTATED.